Pachyonychia congenita (PC) is a rare, autosomal dominant keratin disorder that typically affects the nails, skin, oral mucosa, larynx, hair, and teeth. Currently there are two distinct syndromes of PC that are recognized: PC-1 or Jadassohn-Lewandowsky type, and PC-2, or Jackson-Lawler type. The PC-1 clinical phenotype is associated with mutations in the genes encoding the K6a or K16 keratins whereas the PC-2 phenotype is associated with mutations in the genes encoding the K6b or K17 keratins. There are at least 20 known genetic mutations that cause PC and a high percentage of these are mononucleotide mutations, although other mutations can also cause the disorder. The most common symptoms associated with PC include thickened fingernails and toenails, plantar keratoderma (blisters and thick calluses on the soles of the feet), palmar keratoderma (blisters and thick calluses on the palms of the hands), oral leukokeratosis (thick white growth on tongue or cheeks), follicular keratosis (bumps formed around hair follicles), pilosebaceous cyst formation (including steatocystoma type), laryngeal involvement (hoarseness), hyperhidrosis (excessive sweating on feet or hands), and natal or prenatal teeth.
There are currently no known specific treatments for PC. Available treatments generally are directed at specific manifestations of the disorder but generally do not affect the underlying cause. As individual patients are generally troubled by different manifestations of the disease, no single treatment plan is effective for treating the disorder as a whole. Treatment options for PC fall into four broad categories, non-invasive (mechanical), invasive (surgical), chemical, and pharmacological. Currently no treatment options are available for PC which address the underlying cause of the disorder and therefore prevent the occurrence of symptoms.